Fan Out Package Structure and Methods of Forming

ABSTRACT

An embodiment is a structure comprising a die having a pad on a surface and an encapsulant at least laterally encapsulating the die. The pad is exposed through the encapsulant. The structure further includes a first dielectric layer over the encapsulant and the die, a first conductive pattern over the first dielectric layer, and a second dielectric layer over the first conductive pattern and the first dielectric layer. The first dielectric layer and the second dielectric layer have a first opening to the pad of the die. The structure further includes a second conductive pattern over the second dielectric layer and in the first opening. The second conductive pattern adjoins a sidewall of the first dielectric layer in the first opening and a sidewall of the second dielectric layer in the first opening.

BACKGROUND

Semiconductor devices are used in a variety of electronic applications,such as personal computers, cell phones, digital cameras, and otherelectronic equipment, as examples. Semiconductor devices are typicallyfabricated by sequentially depositing insulating or dielectric layers,conductive layers, and semiconductive layers of material over asemiconductor substrate, and patterning the various material layersusing lithography to form circuit components and elements thereon.Dozens or hundreds of integrated circuits are typically manufactured ona single semiconductor wafer. The individual dies are singulated bysawing the integrated circuits along a scribe line. The individual diesare then packaged separately, in multi-chip modules, or in other typesof packaging, for example.

The semiconductor industry continues to improve the integration densityof various electronic components (e.g., transistors, diodes, resistors,capacitors, etc.) by continual reductions in minimum feature size, whichallow more components to be integrated into a given area. These smallerelectronic components such as integrated circuit dies may also requiresmaller packages that utilize less area than packages of the past, insome applications.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present embodiments, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIGS. 1 through 8 are various cross sectional views of structures duringa first process according to an embodiment;

FIGS. 9 and 10 are various cross sectional views of structures during asecond process according to an embodiment; and

FIG. 11 is an expanded view of a via according to an embodiment.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the present embodiments are discussed in detailbelow. It should be appreciated, however, that the present disclosureprovides many applicable inventive concepts that can be embodied in awide variety of specific contexts. The specific embodiments discussedare merely illustrative of specific ways to make and use the disclosedsubject matter, and do not limit the scope of the different embodiments.

Embodiments will be described with respect to a specific context, namelya fan-out package structure. Other embodiments may also be applied,however, to other package structures. Figures and discussion belowillustrate simplified structures so as to not obscure various featuresand to omit redundant features that would be apparent to a person ofordinary skill in the art. Like reference numbers in the figures referto like components. Although method embodiments may be described asbeing performed in a particular order, other embodiments may beperformed in any logical order.

FIGS. 1 through 8 illustrate various cross sectional views of structuresduring a first process according to an embodiment. FIG. 1 illustratestwo dies 24 with a surrounding molding compound 30 during processing.The dies 24 each comprise a pad 26, such as an aluminum pad, and apassivation layer 28 over a top surface of the die 24. The dies 24 maybe, for example, a logic integrated circuit, a memory die, an analogdie, or any other die. The dies 24 may comprise a semiconductorsubstrate, such as a bulk semiconductor substrate,semiconductor-on-insulator substrate, or the like, on which activedevices, such as transistors, and/or passive devices, such ascapacitors, inductors, or the like, are formed according tosemiconductor processes. Metallization layers may be on thesemiconductor substrate and may comprise interconnect structures toelectrically couple devices together and/or to a pad 26.

In an example, the dies 24 are formed as part of a wafer. A sacrificiallayer, which may comprise a dry film or a wet film formed by coating,laminating, printing, or the like, is formed over the passivation layer28 and pad 26 of each die 24 of the wafer. The sacrificial layer can becured by ultraviolet (UV) radiation, an oven process, or the like. Thewafer is then singulated to form individual dies 24. The dies 24 areplaced on a carrier substrate 20 using, for example, a pick-and-placetool, and the dies 24 are adhered to the carrier substrate 20 by a dieattach film 22, such as any suitable adhesive, such as UV glue (whichloses its adhesive property when exposed to UV lights), or film on wire(FOW) materials.

A molding compound 30 is formed at least laterally encapsulating thedies 24. The molding compound 30 may be formed using compressionmolding, lamination, or the like. The molding compound 30 may be anepoxy-based complex or the like. The molding compound 30 may be curedusing, for example, a thermal process at a temperature between about120° C. and about 330° C. The molding compound 30 may undergo a grindingprocess to expose the sacrificial layer over the dies 24. Thesacrificial layer may be removed using a solvent, chemicals, or thelike. In an example, a wet etch selective to the sacrificial layer, suchas a dilute KOH solution that is, for example, about 3% to about 5% KOH,is used to remove the sacrificial layer. Thus, the structure illustratedin FIG. 1 may be formed.

In FIG. 2, a first dielectric layer 32 is formed over the passivationlayers 28 and pads 26 of the dies 24 and over the molding compound 30.The first dielectric layer 32 may comprise a polybenzoxazole (PBO),polyimide, benzocyclobutene (BCB), the like, or a combination thereof.The first dielectric layer 32 can be deposited by a spin coatingprocess, laminating process, the like, or a combination thereof.

In FIG. 3, a first conductive layer 34 is formed on the first dielectriclayer 32. The first conductive layer 34 comprises various traces. Theinset 35 is a plan view and illustrates a trace 37 connected to a viaconnecting portion 36 formed directly over a respective pad 26. The viaconnecting portion 36 has an opening with a width 38. The via connectingportion 36 is illustrated as a ring or ring-like shape, and in otherembodiments, the opening in the via connecting portion 36 may be arectangular or square-like shape, a triangular shape, a hexagonal shape,an octagonal shape, or the like. Also, the via connecting portion 36 isillustrated as an enclosed shape, and in other embodiments, the viaconnecting portion 36 may be broken or disconnected.

The first conductive layer 34 in an example comprises a metal such ascopper, titanium, the like, or a combination thereof, formed by aplating process, such as electroless plating, electroplating, or thelike. For example, a seed layer is deposited over the first dielectriclayer 32. The seed layer can be copper, titanium, a combination ofcopper and titanium (Ti/Cu), the like, or a combination thereofdeposited by atomic layer deposition (ALD), sputtering, another physicalvapor deposition (PVD) process, or the like. A photoresist is depositedand patterned exposing the pattern for the first conductive layer 34that is desired, such as by an acceptable photolithography technique. Aconductive material, such as copper, aluminum, the like, or acombination thereof, is deposited on the seed layer by electrolessplating, electroplating, or the like. The photoresist is removed, suchas an appropriate photoresist stripping process. Remaining exposed seedlayer portions are removed, such as by a wet or dry etch.

In FIG. 4, a second dielectric layer 40 is formed over the firstdielectric layer 32 and the first conductive layer 34. The seconddielectric layer 40 may comprise a PBO, polyimide, BCB, the like, or acombination thereof. The second dielectric layer 40 can be deposited bya spin coating process, laminating process, the like, or a combinationthereof.

In FIG. 5, openings 42 are formed through the second dielectric layer 40to the first dielectric layer 32 and/or the first conductive layer 34,such as to via connecting portions 36, using an acceptablephotolithography technique, such as including exposing to light theportions of the second dielectric layer 40 where the openings 45 are tobe formed.

In FIG. 6, openings 44 are formed through the first dielectric layer 32to the pads 26. In an example, the openings 44 are formed using anetching process. The etching can be anisotropic and can include areactive ion etching (RIE), a capacitive coupled plasma (CCP) etching,an inductive coupled plasma (ICP), the like, or a combination thereof.In other examples, other acceptable methods may be used, such as laserdrilling. The first conductive layer 34, such as the via connectingportion 36 may act as a mask during the removing the first dielectriclayer 32 to form the openings 44.

In FIG. 7, a second conductive layer 46 is formed on the seconddielectric layer 40 and in the openings 44. The second conductive layer46 comprises various traces and/or bond pads for balls. The secondconductive layer 46 in an example comprises a metal such as copper,titanium, the like, or a combination thereof, formed by a platingprocess, such as electroless plating, electroplating, or the like. Forexample, a seed layer is deposited over the second dielectric layer 40and in the openings 44. The seed layer can be copper, titanium, acombination of copper and titanium (Ti/Cu), the like, or a combinationthereof deposited by ALD, sputtering, another PVD process, or the like.A photoresist is deposited and patterned exposing the pattern for thesecond conductive layer 46 that is desired, such as by an acceptablephotolithography technique. A conductive material, such as copper,aluminum, the like, or a combination thereof, is deposited on the seedlayer by electroless plating, electroplating, or the like. Thephotoresist is removed, such as an appropriate photoresist strippingprocess. Remaining exposed seed layer portions are removed, such as by awet or dry etch. Vias are formed in the openings 44 that connect arespective pad 26, via connecting portion 36 of the first conductivelayer 34, and a portion of the second conductive layer 46.

In FIG. 8, a ball 48 is formed on a bond pad of the second conductivelayer 46. The ball 48 may comprise solder, such as lead-free solder, andmay be formed using an acceptable ball drop process. A bracing material50 may be formed over the second conductive layer 46 and the seconddielectric layer 40 and around a portion of the ball 48. The bracingmaterial 50 may comprise a molding compound or the like that providesstructural support.

FIGS. 9 and 10 illustrate various cross sectional views of structuresduring a second process according to an embodiment. The second processproceeds through FIGS. 1 through 4 as discussed above. In FIG. 9, a masklayer 60 having openings 62 is formed over the second dielectric layer40. The mask layer 60 may comprise silicon nitride, silicon oxynitride,a photosensitive film (a dry film or a wet film), the like, or acombination thereof, and may be formed using a chemical vapor deposition(CVD), coating, laminating, the like, or a combination thereof. Theopenings 62 can be formed using an acceptable photolithography andetching process, such as using RIE, CCP, ICP, the like, or a combinationthereof. In this embodiment, the second dielectric layer 40 may beformed with an initial thickness less than that in the first processbecause, for example, the mask layer 60 may prevent a loss of thicknessof the second dielectric layer 40 when forming the openings 64 ascompared to the formations of openings 44 in FIG. 6.

In FIG. 10, openings 64 are formed through the second dielectric layer40 and the first dielectric layer 32 to the pads 26 using the mask layer60. In an example, the openings 64 are formed using an etching processthrough the second dielectric layer 40 and the first dielectric layer32. The etching can be anisotropic and can include RIE, CCP, ICP, thelike, or a combination thereof. In other examples, other acceptablemethods may be used, such as laser drilling. The first conductive layer34, such as the via connecting portion 36 may act as a mask during theremoving the first dielectric layer 32 to form the openings 64. The masklayer 60 may be removed after forming the openings 64, such as by usingan etch that is selective to the mask layer 60. The second process thencontinues through FIGS. 7 and 8 as discussed above.

In each of the first and second processes, the carrier substrate 20 maybe removed, such as by exposing the die attach film 22 to a solvent orUV light. Hence, a package may comprise a structure as illustrated inFIG. 8 without the carrier substrate 20 and the die attach film 22.

FIG. 11 illustrates an expanded view of a via formed according to theprocesses discussed above. As shown, the first conductive layer 34includes a first seed layer 70 and a first main layer 72, and the secondconductive layer 46 includes a second seed layer 74 and a second mainlayer 76. The first conductive layer 34, which includes the viaconnecting portion 36, extends along a top surface of the firstdielectric layer 32 and does not extend along sidewalls of the firstdielectric layer 32. The second conductive layer 46 extends along a topsurface of the second dielectric layer 40, adjoins sidewalls of thesecond dielectric layer 40, the first conductive layer 34 (e.g., the viaconnecting portion 36), and the first dielectric layer 32, and adjoins atop surface of the pad 26. The bracing material 50 may fill any unfilledportion of the via, for example, as shown in FIG. 11.

Embodiments may achieve advantages. For example, by having a via formedwith only one conductive layer along sidewalls of an opening, an aspectratio of the via may be decreased. This may decrease an opening size ofthe via. Thus, a pad on the die may be smaller. Additionally, costs maybe reduced using some embodiments.

An embodiment is a structure comprising a die having a pad on a surfaceand an encapsulant at least laterally encapsulating the die. The pad isexposed through the encapsulant. The structure further includes a firstdielectric layer over the encapsulant and the die, a first conductivepattern over the first dielectric layer, and a second dielectric layerover the first conductive pattern and the first dielectric layer. Thefirst dielectric layer and the second dielectric layer have a firstopening to the pad of the die. The structure further includes a secondconductive pattern over the second dielectric layer and in the firstopening. The second conductive pattern adjoins a sidewall of the firstdielectric layer in the first opening and a sidewall of the seconddielectric layer in the first opening.

Another embodiment is structure comprising a package and an externalelectrical connector on the package. The package comprises a diecomprising a pad, an encapsulant around the die, and a dielectricmulti-layer structure over the die and the encapsulant. The dielectricmulti-layer structure comprises a first conductive pattern in thedielectric multi-layer structure and a second conductive pattern on thedielectric multi-layer structure. A first opening is defined through thedielectric multi-layer structure to the pad. At least a portion of thefirst conductive pattern defines at least a portion of the firstopening. At least a portion of the second conductive pattern is in thefirst opening and adjoins sidewalls of the dielectric multi-layerstructure. The first conductive pattern does not extend along thesidewalls of the dielectric multi-layer structure in the first opening.

A further embodiment is a method comprising encapsulating a die with anencapsulant, a pad of the die being exposed through the encapsulant;forming a first dielectric layer over the encapsulant and the die;forming a first conductive pattern over the first dielectric layer;forming a second dielectric layer over the first conductive pattern andthe first dielectric layer; after forming the first conductive patternand the second dielectric layer, forming an opening through the seconddielectric layer and the first dielectric layer to the pad; and forminga second conductive pattern over the second dielectric layer and in theopening.

Although the present embodiments and their advantages have beendescribed in detail, it should be understood that various changes,substitutions and alterations can be made herein without departing fromthe spirit and scope of the disclosure as defined by the appendedclaims. Moreover, the scope of the present application is not intendedto be limited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed, that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present disclosure.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps.

What is claimed is:
 1. A structure comprising: a die having a pad on asurface; an encapsulant at least laterally encapsulating the die, thepad being exposed through the encapsulant; a first dielectric layer overthe encapsulant and the die; a first conductive pattern over the firstdielectric layer; a second dielectric layer over the first conductivepattern and the first dielectric layer, the first dielectric layer andthe second dielectric layer having a first opening to the pad of thedie; and a second conductive pattern over the second dielectric layerand in the first opening, the second conductive pattern adjoining asidewall of the first dielectric layer in the first opening and asidewall of the second dielectric layer in the first opening.
 2. Thestructure of claim 1, wherein the first conductive pattern comprises aconnecting portion, the connecting portion having a second opening, thesecond opening defining the first opening in the first dielectric layer,a sidewall of the connecting portion adjoining the second conductivepattern in the first opening.
 3. The structure of claim 2, wherein theconnecting portion comprises a ring having the second opening.
 4. Thestructure of claim 2, wherein the connecting portion comprises arectangular shape, a triangular shape, a hexagonal shape, an octagonalshape, or a combination thereof.
 5. The structure of claim 2, whereinthe connecting portion has a continuous portion enclosing the secondopening.
 6. The structure of claim 2, wherein the connecting portion hasdiscontinuous portions around the second opening.
 7. The structure ofclaim 1, wherein the second conductive pattern comprises a seed layerand a main layer over the seed layer.
 8. The structure of claim 1further comprising: an external electrical connector on the secondconductive pattern; and a bracing material over the second dielectriclayer and the second conductive pattern and around at least a portion ofthe external electrical connector.
 9. A structure comprising: a packagecomprising: a die comprising a pad, an encapsulant around the die, and adielectric multi-layer structure over the die and the encapsulant, thedielectric multi-layer structure comprising a first conductive patternin the dielectric multi-layer structure and a second conductive patternon the dielectric multi-layer structure, a first opening being definedthrough the dielectric multi-layer structure to the pad, at least aportion of the first conductive pattern defining at least a portion ofthe first opening, at least a portion of the second conductive patternbeing in the first opening and adjoining sidewalls of the dielectricmulti-layer structure, the first conductive pattern not extending alongthe sidewalls of the dielectric multi-layer structure in the firstopening; and an external electrical connector on the package.
 10. Thestructure of claim 9, wherein the first conductive pattern comprises aconnecting portion, the connecting portion having a second opening, thesecond opening defining at least the portion of the first opening, asidewall of the connecting portion adjoining the second conductivepattern in the first opening.
 11. The structure of claim 10, wherein theconnecting portion comprises a ring having the second opening.
 12. Thestructure of claim 10, wherein the connecting portion has a continuousportion enclosing the second opening.
 13. The structure of claim 9,wherein each of the first conductive pattern and the second conductivepattern comprises a seed layer and a main layer over the seed layer. 14.A method comprising: encapsulating a die with an encapsulant, a pad ofthe die being exposed through the encapsulant; forming a firstdielectric layer over the encapsulant and the die; forming a firstconductive pattern over the first dielectric layer; forming a seconddielectric layer over the first conductive pattern and the firstdielectric layer; after forming the first conductive pattern and thesecond dielectric layer, forming an opening through the seconddielectric layer and the first dielectric layer to the pad; and forminga second conductive pattern over the second dielectric layer and in theopening.
 15. The method of claim 14, wherein the first conductivepattern comprises a connecting portion, the connecting portion beingused as a mask when forming the opening through the first dielectriclayer.
 16. The method of claim 14, wherein the first conductive patterncomprises a connecting portion, the connecting portion comprises a ring.17. The method of claim 14, wherein the forming the opening comprises:lithographically patterning the second dielectric layer; and etching thefirst dielectric layer.
 18. The method of claim 14, wherein the formingthe opening comprises: forming a mask over the second dielectric layer;and etching the second dielectric layer and the first dielectric layer.19. The method of claim 14, wherein the second conductive pattern in theopening adjoins sidewalls of the first dielectric layer and the seconddielectric layer.
 20. The method of claim 14 further comprising: formingan external electrical connector electrically coupled to the secondconductive pattern; and forming a bracing material over the seconddielectric layer and the second conductive pattern and around at least aportion of the external electrical connector.